Low pressure drop reforming exchanger
View Patent ↗Syngas production process and reforming exchanger. The process involves passing a first portion of hydrocarbon feed mixed with steam and oxidant through an autothermal catalytic steam reforming zone to form a first reformed gas of reduced hydrocarbon content, passing a second portion of the hydrocarbon feed mixed with steam through an endothermic catalytic steam reforming zone to form a second reformed gas of reduced hydrocarbon content, and mixing the first and second reformed gases and passing the resulting gas mixture through a heat exchange zone for cooling the gas mixture and thereby supplying heat to the endothermic catalytic steam reforming zone. The endothermic catalytic steam reforming zone and the heat exchange zone are respectively disposed tube side and shell side within a shell-and-tube reforming exchanger. The reforming exchanger comprises a plurality of tubes packed with low pressure drop catalyst-bearing monolithic structures wherein an inside diameter of the tubes is less than 4 times a maximum edge dimension of the catalyst structures.
1. A syngas production process, comprising:
passing a first portion of a hydrocarbon feed mixed with steam and oxidant through an autothermal catalytic steam reforming zone to form a first reformed gas of reduced hydrocarbon content;
passing a second portion of the hydrocarbon feed mixed with steam through an endothermic catalytic steam reforming zone to form a second reformed gas of reduced hydrocarbon content;
mixing the first and second reformed gases and passing the resulting gas mixture through a heat exchange zone for cooling the gas mixture and supplying heat to the endothermic catalytic steam reforming zone;
wherein the endothermic catalytic steam reforming zone and the heat exchange zone are respectively disposed tube side and shell side within a shell-and-tube reforming exchanger comprising a plurality of tubes packed with catalyst-bearing monolithic structures, the tubes having an inside diameter that is not more than 4 times a maximum edge dimension of the catalyst structures; and
recovering syngas comprising the cooled gas mixture.
2. The process of claim 1 wherein the tubes have an L t /D t ratio of at least 300 wherein L t is taken as the length of the catalyst bearing extent of the tubes and D t is the inside diameter of the tubes.
3. The process of claim 2 wherein an overall heat transfer rate is at least 5 percent greater for a given pressure drop than Raschig rings measuring 0.31-in. long by 0.31-in. outside diameter by 0.125-in. inside diameter in tubes having an inside diameter of 2-in.
4. The process of claim 3 wherein a surface area of the catalyst-bearing monolithic structures for a given capacity is less than the Raschig rings in the 2-in. inside diameter tubes.
5. The process of claim 4 wherein a catalyst volume of the catalyst-bearing monolithic structures for the given capacity is less than the Raschig rings in the 2-in. inside diameter tubes.
6. The process of claim 2 wherein the catalyst-bearing monolithic structures comprise ceramic foam made by filling voids in a sponge substrate with a fluidized ceramic and burning the substrate away to form the ceramic foam.
7. The process of claim 6 wherein the ceramic foam is made in sheets, plugs are cut from the sheet having a diameter less than a thickness, and a plurality of the plugs are stacked end-to-end in each tube.
8. The process of claim 2 wherein the catalyst-bearing monolithic structures comprise a twisted tape insert with a wash-coated surface impregnated with a nickel-containing catalyst.
9. The process of claim 2 wherein the catalyst-bearing monolithic structures comprise a central longitudinal runner, a plurality of bristles extending transversely therefrom and the bristles are wash-coated and impregnated with a nickel-containing catalyst.
10. The process of claim 1 wherein the catalyst-bearing monolithic structures comprise a twisted tape insert.
11. The process of claim 1 wherein the catalyst-bearing monolithic structures comprise a central longitudinal runner and a plurality of bristles extending transversely therefrom.
12. The process of claim 1 wherein the catalyst-bearing monolithic structures comprise ceramic foam.
13. The process of claim 1 wherein the catalyst-bearing monolithic structures comprise Raschig rings.
14. The process of claim 1 wherein the inside diameter of the tubes is from 0.75to 1.55 inches.
15. Apparatus for reforming a hydrocarbon to produce syngas, comprising:
means for passing a first portion of a hydrocarbon feed mixed with steam and oxidant through an autothermal catalytic steam reforming zone to form a first reformed gas of reduced hydrocarbon content;
means for passing a second portion of the hydrocarbon feed mixed with steam through an endothermic catalytic steam reforming zone to form a second reformed gas of reduced hydrocarbon content;
means for mixing the first and second reformed gases and passing the resulting gas mixture through a heat exchange zone for cooling the gas mixture and supplying heat to the endothermic catalytic steam reforming zone;
wherein the endothermic catalytic steam reforming zone and the heat exchange zone are respectively disposed tube side and shell side within a shell-and-tube reforming exchanger comprising a plurality of tubes packed with catalyst-bearing monolithic structures, the tubes having an inside diameter that is not more than 4 times a maximum edge dimension of the catalyst structures; and
means for recovering syngas comprising the cooled gas mixture.
16. The apparatus of claim 15 wherein the tubes have an L t /D t ratio of at least 300 wherein L t is taken as the length of the catalyst bearing extent of the tubes and D t is the inside diameter of the tubes.
17. The apparatus of claim 16 wherein an overall heat transfer rate is at least 5 percent greater for a given pressure drop than Raschig rings measuring 0.31-in. long by 0.31-in. outside diameter by 0.125-in. inside diameter in tubes having an inside diameter of 2-in.
18. The apparatus of claim 17 wherein a surface area of the catalyst-bearing monolithic structures for a given capacity is less than the Raschig rings in the 2-in. inside diameter tubes.
19. The apparatus of claim 18 wherein a catalyst volume of the catalyst-bearing monolithic structures for the given capacity is less than the Raschig rings in the 2-in. inside diameter tubes.
20. The apparatus of claim 16 wherein the catalyst-bearing monolithic structures comprise ceramic foam made by filling voids in a sponge substrate with a fluidized ceramic and burning the substrate away to form the ceramic foam.
21. The apparatus of claim 20 wherein the ceramic foam is made in sheets, plugs are cut from the sheet having a diameter less than a thickness, and a plurality of the plugs are stacked end-to-end in each tube.
22. The apparatus of claim 16 wherein the catalyst-bearing monolithic structures comprise a twisted tape insert with a wash-coated surface impregnated with a nickel containing catalyst.
23. The apparatus of claim 16 wherein the catalyst-bearing monolithic structures comprise a central longitudinal runner, a plurality of bristles extending transversely therefrom and the bristles are wash-coated and impregnated with a nickel-containing catalyst.
24. The apparatus of claim 15 wherein the catalyst-bearing monolithic structures comprise a twisted tape insert.
25. The apparatus of claim 15 wherein the catalyst-bearing monolithic structures comprise a central longitudinal runner and a plurality of bristles extending transversely therefrom.
26. The apparatus of claim 15 wherein the catalyst-bearing monolithic structures comprise ceramic foam.
27. The apparatus of claim 15 wherein the catalyst-bearing monolithic structures comprise Raschig rings.
28. The apparatus of claim 15 wherein the inside diameter of the tubes is from 19 to 39 mm (0.75 to 1.55 inches).